Recently, Dr Jingjing Cao from Jiangnan University, in collaboration with German researchers, successfully developed a low-cost, earth-abundant 'unsaturated coordination defect zinc oxide nanosheet catalyst', providing a new solution for the efficient and green recycling of waste polyester plastics under mild conditions.
The related research results were published in Nature Communications.
Polyester plastics have huge annual production, but traditional chemical recycling methods face problems such as high energy consumption, equipment corrosion and wastewater treatment difficulties. In this study, the team designed a zinc oxide catalyst with special defect structures on its surface. They vividly described it as a 'molecular scalpel', with surface defect sites acting like highly active 'graspers' that preferentially adsorb and activate water and oxygen molecules, enabling precise cleavage of polyester bonds under near-neutral aqueous conditions without the need for organic solvents or strong bases.
Experiments showed that in an air environment at 190°C, the catalytic system could completely depolymerise polyethylene terephthalate (PET) in just six hours, with a selectivity for terephthalic acid exceeding 99%. Moreover, the catalyst exhibited excellent 'substrate universality', efficiently processing both ordinary mineral water bottles and waste textiles containing dyes and other impurities, maintaining terephthalic acid recovery rates above 98%.
The technology is also applicable to the highly selective monomer recovery of other polyester wastes. In terms of environmental friendliness, the catalyst remained stable after five continuous cycles, and no harmful zinc ion leaching was detected during the reaction, avoiding secondary pollution. Currently, the research team has completed laboratory-scale experiments at the 40-gram level, successfully converting waste plastics into high-purity raw materials and reprocessing them into recycled PET.
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